The Federal Election Commission reports show Warren has raised $38.5 million in political donations as of mid-October, compared to Brown's $26.7 million. Brown's total doesn't include the $6 million left in his campaign account after the 2010 special election that propelled him into the Senate.

The fundraising reports amid the candidates' final sprints to Election Day in a race closely-watched for its impact on the broader fight for control of the Senate. Republicans must gain four seats to win the majority if President Barack Obama is re-elected, or three if Republican hopeful and former Massachusetts governor Mitt Romney prevails.

Despite the campaign cash and messaging, the race in the final stretch was about getting voters to the polls on Tuesday.

Brown embarked on a campaign bus tour with stops in Milford, North Grafton, Framingham and Wakefield, his childhood hometown. The tour is scheduled to conclude Monday night in Wrentham, where Brown lives.

Warren's Thursday schedule included stops in Quincy, Brockton and New Bedford, as she launched a new radio ad tweaking Brown for refusing a final debate offer.

The fourth debate was planned for Tuesday, but was delayed because of Superstorm Sandy. The gale caused widespread power outages but largely spared Massachusetts the severe damage seen in New York, New Jersey and other states.

Warren agreed to a rescheduled debate on Thursday, but Brown declined despite having twice pledged, once on Friday and again on Monday, that a final debate would happen. A Brown aide later pointed to a scheduling conflict with his bus tour.

In Warren's ad, a narrator faults Brown for declining the debate.

"Scott Brown backed out of his final debate with Elizabeth Warren," the narrator says. "Rather than discuss the issues, he had to grab a bus. With his record, you can't blame him for hitting the road."

Brown also released two new radio ads Thursday, including one featuring former Democratic Boston Mayor Ray Flynn praising Brown as a "sincere, independent, honest, hard-working voice" in the Senate. Flynn has offered repeated testimonials for Brown during the campaign.

A second radio ad mirrors Brown's closing television ad released on Wednesday in which Brown pledges to put "people ahead of politics" and "keep that independent tradition alive in Massachusetts."

The new campaign fundraising reports show that during the first 17 days of October, Warren added nearly $2.5 million to her fundraising total. During the same period, Brown collected nearly $1.6 million.

The reports also show both candidates are spending at a furious pace.

As of Oct. 17, Warren had just $3.5 million left in her account while Brown had $3.7 million left. On Thursday, the Brown campaign sent an email to supporters asking for donations to help keep his final television ad on the air.

The $68 million spent so far shatters all previous fundraising and spending records in Massachusetts. Even more remarkable is the fact that neither candidate has contributed any money to their own campaigns.

The campaign reports showed that the bulk of money coming into each campaign has been from individual contributors, although both Brown and Warren have also enjoyed support from political action committees.

Warren's report showed that during the election cycle she's collected more than $600,000 from PACs compared to the $3.2 million Brown collected from political action committees.

Both Warren and Brown also are fine-tuning efforts to get their voters to the polls on Tuesday.

Warren campaign officials say they're hoping to knock on a million doors and make 2 million phone calls in the campaign's final days.

Republicans say they've contacted more than 2 million voters and are planning a far more aggressive door-to-door voter turnout drive than two years ago.